Special effects, not visual effects
Once WandaVision gets out into the world, it’s a Marvel production with the visual effects to match. But when it’s inside, and set in a time period before computers were modernized, the producers made sure to use actual, period-accurate special effects. So when you see Wanda in her kitchen (which was actually blue, as you can see in other behind-the-scenes pics) with recipes and lobsters floating and flying around, those are all on wires.
